An interventional study of Modified Twin Block Appliance and Conventional Clear Twin Block Appliance in Skeletal Class II Malocclusion, sponsored by University of Aleppo. Active, not recruiting at 1 site in Syria. Open to participants aged 10 Years to 13 Years. Per ClinicalTrials.gov, last updated 2026-07-14.
Sponsored by University of Aleppo · Not applicable, Interventional, and Treatment
This study aims to evaluate the effectiveness of a modified Twin Block appliance compared to a conventional clear Twin Block appliance in the treatment of skeletal Class II malocclusion caused by mandibular retrusion in growing patients.
This is a two-arm randomized controlled clinical trial including patients aged 10-13 years diagnosed with skeletal Class II malocclusion. Participants will be randomly allocated into two equal groups.
Skeletal, dental, and soft tissue changes will be assessed using lateral cephalometric analysis and cone-beam computed tomography (CBCT). Additionally, temporomandibular joint (TMJ) health, pain perception, and functional tolerance will be evaluated using standardized clinical indices and patient-reported outcome measures.
The study aims to compare the modified appliance with the conventional design in terms of skeletal improvement, TMJ safety, and patient acceptance.
Skeletal and dentofacial anomalies, particularly Class II malocclusion due to mandibular retrusion, represent one of the most prevalent orthodontic problems during growth. Functional appliances, especially the Twin Block appliance, are widely used to enhance mandibular development and correct jaw discrepancies. However, variations in treatment protocols, particularly regarding advancement mechanics and appliance modifications, may influence both skeletal outcomes and temporomandibular joint (TMJ) response.
This study aims to investigate the effects of a modified Twin Block appliance, incorporating progressive mandibular advancement and additional design modifications such as lower lip pads intended to influence muscular activity, compared to a conventional clear Twin Block appliance.
A two-arm randomized controlled trial will be conducted on growing patients aged 10-13 years diagnosed with skeletal Class II malocclusion due to mandibular retrusion. Participants will be randomly allocated into two equal groups using a computer-generated randomization sequence with allocation concealment.
Skeletal and dental changes will be evaluated using lateral cephalometric radiographs and cone-beam computed tomography (CBCT), with particular attention to condylar morphology, joint space dimensions, and craniofacial skeletal relationships. TMJ health will be assessed using the Helkimo Index. Patient comfort, pain perception, and functional adaptation will be evaluated using validated questionnaires administered at multiple time points throughout the treatment period.
Radiographic and clinical assessments will be performed at baseline (T0) and after 7 months of functional appliance therapy (T1). Repeated patient-reported outcome measures will be collected at predefined intervals during treatment.
The objective of this study is to determine whether the modified Twin Block appliance provides superior skeletal and functional outcomes while maintaining temporomandibular joint safety and improving patient tolerance compared to the conventional appliance.
University of Aleppo is the lead sponsor of 9 studies on the registry; 3 are open to participants now.
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Exclusion Criteria:
Patients in this group will be treated using a modified Twin Block appliance incorporating progressive mandibular advancement and lower lip pads designed to influence muscular activity and enhance skeletal effects.
Device: Modified Twin Block Appliance
Patients in this group will be treated using a conventional clear Twin Block functional appliance for correction of skeletal Class II malocclusion.
Device: Conventional Clear Twin Block Appliance
A modified Twin Block functional appliance incorporating progressive mandibular advancement and lower lip pads designed to modify muscular activity and enhance mandibular growth. The appliance is used for the treatment of skeletal Class II malocclusion due to mandibular retrusion in growing patients.
Also known as: Progressive Twin Block
A conventional clear Twin Block functional appliance used for correction of skeletal Class II malocclusion in growing patients. The appliance acts by posturing the mandible forward to stimulate functional and skeletal adaptation.
Also known as: Clear Twin Block
Change in mandibular skeletal position measured by SNB angle on lateral cephalometric radiographs
Assessment of sagittal mandibular skeletal position using the SNB angle (degrees) measured on standardized lateral cephalometric radiographs.
Time frame: Baseline (T0) and after 7 months of treatment (T1)
Change in effective mandibular length measured by Co-Gn distance on lateral cephalometric radiographs
Assessment of mandibular length using the Condylion-Gnathion (Co-Gn) linear measurement in millimeters obtained from lateral cephalometric analysis.
Time frame: Baseline (T0) and after 7 months of treatment (T1)
Change in condylar dimensions assessed using cone-beam computed tomography (CBCT)
Assessment of temporomandibular condylar morphology using CBCT, including condylar length, condylar width, and condylar height measured in millimeters.
Time frame: Baseline (T0) and after 7 months of treatment (T1)
Change in temporomandibular joint spaces assessed using CBCT
Assessment of condylar position within the glenoid fossa using CBCT measurements of anterior joint space (AJS), superior joint space (SJS), posterior joint space (PJS), and medial joint space (MJS), measured in millimeters.
Time frame: Baseline (T0) and after 7 months of treatment (T1)
Temporomandibular joint dysfunction symptoms assessed using the Helkimo Anamnestic Index (Ai)
Assessment of temporomandibular joint dysfunction symptoms using the Helkimo Anamnestic Index questionnaire. The index classifies patients into: * Ai0: no symptoms * Ai1: mild symptoms * Ai2: severe symptoms Higher scores indicate greater temporomandibular dysfunction severity.
Time frame: Baseline (T0) and after 7 months of treatment (T1)
Patient-reported pain intensity assessed using a Numeric Rating Scale (NRS)
Assessment of pain intensity reported by patients using a numeric rating scale ranging from 0 to 10, where 0 indicates no pain and 10 indicates maximum pain.
Time frame: 1 week, 2 weeks, 6 weeks, 3 months, and 6 months after appliance insertion
Patient-reported discomfort and functional limitation assessed using a validated questionnaire
Assessment of appliance-related discomfort and functional or social impairment using a validated questionnaire adapted from Sergl and Zentner (1998), modified by Idris et al. (2012). The questionnaire evaluates pressure sensation, tooth sensitivity, speech impairment, swallowing difficulty, mouth restriction sensation, and social confidence using a numeric rating scale from 0 to 10. Higher scores indicate greater discomfort and poorer appliance acceptance.
Time frame: 1 week, 2 weeks, 6 weeks, 3 months, and 6 months after appliance insertion
Change in lower incisor inclination measured by IMPA on lateral cephalometric radiographs
Assessment of lower incisor inclination using the Incisor Mandibular Plane Angle (IMPA) measured in degrees on lateral cephalometric radiographs.
Time frame: Baseline (T0) and after 7 months of treatment (T1)
Change in upper incisor inclination measured by U1-SN angle on lateral cephalometric radiographs
Assessment of upper incisor inclination using the upper incisor to SN plane angle (U1-SN) measured in degrees on lateral cephalometric radiographs.
Time frame: Baseline (T0) and after 7 months of treatment (T1)
Change in overjet measured on lateral cephalometric radiographs
Assessment of overjet as the horizontal distance between upper and lower incisors measured in millimeters on lateral cephalometric radiographs.
Time frame: Baseline (T0) and after 7 months of treatment (T1)
Change in overbite measured on lateral cephalometric radiographs
Assessment of overbite as the vertical overlap between upper and lower incisors measured in millimeters on lateral cephalometric radiographs.
Time frame: Baseline (T0) and after 7 months of treatment (T1)
Change in sagittal molar relationship measured on lateral cephalometric radiographs
Assessment of sagittal molar relationship using linear measurements in millimeters between upper and lower first molars on lateral cephalometric radiographs.
Time frame: Baseline (T0) and after 7 months of treatment (T1)
Plan to share: No — Individual participant data will not be shared due to patient privacy and confidentiality considerations. The study involves pediatric orthodontic patients, and data will be reported in aggregate form only.
This study is active, not recruiting, as verified in Jul 2026. You cannot join it, but the record below documents what was studied.
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Overbite
University of Aleppo